The Dangers of Replacing an Outdoor Unit on an Older Air Conditioning System to Save Money

September 9, 2021

When it’s time to replace the outdoor unit on your air conditioning system, you may be tempted to save money by replacing just this unit. However, the indoor and outdoor units work together, and replacing one without replacing the other can be detrimental to your system and end up costing you more money.

How Air Conditioners Work

Air conditioners work by removing heat from inside the home. The refrigerant flows through copper tubing as it makes its way through the system. When the refrigerant reaches the indoor evaporator coil, it absorbs heat and transfers the heat to the outdoor unit. The compressor squeezes the liquid refrigerant at the condenser, and the absorbed heat is then released outside. All these actions are performed simultaneously, and they continue until the home is sufficiently cooled.

The Importance of Matching Components

While it’s initially cheaper to replace just the outdoor unit, you will encounter problems with your system much more quickly. The system won’t run as smoothly and will wear down more quickly, both of which will cost additional money to fix.

It’s hard to match new and old evaporator and condenser coils for the following reasons:

  • Newer coils are more efficient than older ones. When the old and new coils are matched, it places undue pressure on the system. The system won’t be as capable of sufficiently cooling the air, which leads to higher energy consumption. It can also cause certain parts like the motor to fail.
  • Air handler/evaporator units now have new technologies that help them achieve higher SEER ratings (season energy efficiency ratio). When these units are matched with older condenser coils, they can’t reach their expected SEER.
  • Coils manufactured today have grooved surfaces, increased surface space, efficiently designed fins, and enhanced tubing, all of which increase performance levels. Older coils can’t keep up with these features, so they aren’t compatible with the new coils.
  • New units have thermal expansion valves that have better control of the refrigerant and thus boost performance. The units have a hard shut-off that helps the TXV operate well. The shut-off valve is harmful to older compressors because it limits the refrigerant’s movement to the compressor.

Industry Testing

Tests have been performed by manufacturers that were judged against industry standards set forth by the American Society of Heating, Refrigeration, and Air Conditioning Engineers. These tests have determined what can go wrong when components are mismatched. The negative results included a significantly lower operational efficiency, a lower cooling capacity, and an undependable HVAC system.

Instead of replacing just the outdoor unit on your older air conditioning system, replace the entire system. This will save you money, as your air conditioner will properly heat and cool your home.